A new publication of the Phase III AstraZeneca candidate vaccine found that it not only protects people from serious illness and death but also substantially slows the transmission of the virus. The (not yet peer-reviewed) study was published in The Lancet this week.
This study was different from some clinical trials in that the research team measured the impact on transmission by swabbing participants every week. They found a 67% reduction in positive swabs among those vaccinated compared to the placebo group.
The team found that a single dose of the vaccine was 76% effective at preventing Covid-19.
Interestingly, they also found that the vaccine is more effective when the interval between the two shots was longer than the normal 28-day gap. The vaccine was 82% effective when there was 3 months between the 1st and 2nd jab compared to 55% when the doses were given less than six weeks apart.
AstraZeneca says they’ll have enough data by early March to ask the FDA for EUA. The UK authorized the vaccine before New Years and has deployed missions of doses. The E.U. authorized the vaccine last week. I can’t figure out why it’s taking so long in the U.S.
HHS has a contract for delivery of 300M doses of the vaccine but neither the company nor HHS has said when and in what quantities those doses will be available after the vaccine is approved.
Below is an excerpt from the study:
“Vaccine efficacy after a single standard dose of vaccine from day 22 to day 90 post vaccination was 76% (59%, 86%), and modelled analysis indicated that protection did not wane during this initial 3-month period. Similarly, antibody levels were maintained during this period with minimal waning by day 90 day (GMR 0.66, 95% CI 0.59, 0.74). In the SD/SD group, after the second dose, efficacy was higher with a longer prime-boost interval: VE 82.4% 95%CI 62.7%, 91.7% at 12+ weeks, compared with VE 54.9%, 95%CI 32.7%, 69.7% at <6 weeks.